1. Technical Field
The present invention relates to an induction heating cooker operable to perform induction heating of a cooking container.
2. Background Art
In recent years, an induction heating cooker which performs induction heating of cooking containers with a heating coil, such as pans and frying pans, has been widely used in ordinary households and business kitchens. An induction heating cooker detects a temperature of a bottom surface of a cooking container and controls a heating coil such that the detected temperature is coincident with a set temperature.
For example, JP-A-64-33881 (patent document 1) describes an induction heating cooker which is provided with a temperature detection section at a predetermined position on a lower surface of a top plate in order to detect the temperature of the bottom surface of the cooking container. The induction heating cooker starts heating with a predetermined amount of heating electric power at first, and then temporarily stops the heating if a temperature gradient in the bottom surface of the cooking container exceeds a predetermined temperature gradient. Thereafter, heating is restarted by reducing an amount of heating output by half. After heating is restarted, if the detected temperature exceeds a set temperature, the heating is stopped, and if the detected temperature becomes lower than the set temperature, the heating is restarted, so that the temperature of the cooking container is maintained at the set temperature.
However, in cases where the temperature detection section detects the temperature of a cooking container by detecting the temperature at a predetermined position on a lower surface of a top plate, as in the induction heating cooker in the patent document 1, there have been cases where the temperature detected by the temperature detection section is different from the actual temperature gradient in the cooking container or temporarily cannot follow the actual temperature of the cooking container.
For example, when a pan is heated in an empty state at the start of heating, a large temperature gradient actually occurs. However, when the bottom of the pan is warped in a convex shape and there is a large gap between the pan bottom surface and the top plate, the temperature of the pan cannot be easily transferred to the top plate, thereby causing a smaller temperature gradient to be detected. Therefore, the heating is tardily stopped, thereby inducing the problem that the temperature of the pan reaches a high temperature.
Further, when the pan bottom has a small thickness, the temperature of the pan bottom rapidly rises. However, even if the temperature of the pan bottom rapidly rises, since time is required for transferring heat to the bottom surface of the top plate, the temperature detected by the temperature detection section temporarily cannot follow the actual temperature. Therefore, there have been cases where, even when the temperature gradient can be properly determined, the determination is temporarily delayed. As a result, the heating is tardily stopped, thereby inducing the problem that the temperature of the pan bottom reaches a high temperature.
As described above, conventional induction heating cookers have induced the problem that pans having pan bottoms warped in convex shapes and pans having pan bottoms with small thicknesses are excessively heated, thereby preventing heating with high efficiency.